Between mid-June 2020 and early March 2021, the American Red Cross tested more than 3.3 million donations from unvaccinated people in 44 states for the presence of Covid-19 antibodies. Overall, about 7.5% of donations tested in that period were positive for Covid-19 antibodies, meaning that donors were probably infected with the coronavirus at some point.
The American Red Cross notes that “a positive antibody test result does not confirm infection or immunity”, but it can indicate whether a person has been exposed to the coronavirus, “regardless of whether the individual develops symptoms”. The prevalence of antibodies among unvaccinated blood donors has increased over time, as cases have increased across the country.
According to data shared with CNN by email, about 1.5% of donations tested in the first week of July were positive for Covid-19 antibodies. This increased to almost 4% of donations tested in the first week of October, about 12% of donations tested in the first week of January and almost 21% of donations tested in the first week of March.
“Blood donors are not a random sample of the general population, but they are interesting,” said Dr. William Schaffner, longtime adviser to the US Centers for Disease Control and Prevention on vaccines.
Schaffner said there are two things we can be impressed by.
“The first is that a substantial part of the US population has experienced Covid, at least the blood donor population, consciously or unconsciously. The other is that a large proportion of the US population is not – it’s 80%,” he said. . “Therefore, we cannot rely solely on the strategy of allowing collective immunity to occur naturally. We need to vaccinate so that up to 80% of the population is immune.”
Herd immunity is the point at which a sufficient number of people are protected from a disease that cannot spread to the population. This can be achieved when a sufficient number of individuals have antibodies against the virus.
People who recover from the coronavirus have some protection against the virus, although scientists still don’t know how long it lasts or how resistant it is to emerging variants of the coronavirus. Getting a Covid-19 vaccine stimulates the immune system to provide protection artificially.
“Both contribute to the 80% target,” said Schaffner.
The percentage of the US population that needs to be vaccinated for the country to achieve collective immunity remains “an elusive number,” said Anthony Fauci, chief medical advisor to President Joe Biden, at a press conference at the White House on Monday.
“We shouldn’t be so fixated on this indescribable number of collective immunity. We should just be concerned with vaccinating as many people as quickly as possible,” said Fauci, director of the National Institute of Allergy and Infectious Diseases.
“As the herd’s immunity is still a somewhat elusive number, we made a projection of what it probably would be. I have said many times, somewhere between 70% and 85%, but we are not sure about that. we don’t just say to vaccinate as many people as quickly as possible, “said Fauci. “And with each passing day, with more than 2 million doses injecting people, we are getting closer and closer to the control of this pandemic.”
The latest findings from the American Red Cross antibody test among unvaccinated donors reflect more widespread data.
According to a recent report by the Pew Research Center, 1 in 4 Americans claims to have had Covid-19. One in three Hispanic adults claims to have had the virus and younger adults are more likely than adults to say they have the virus. The results suggest that the pandemic has hit most Americans.
In the survey, 67% say they know someone who has been hospitalized or died of the virus. That response echoed in most of all demographic groups, notes the report.
There were about 29.5 million reported cases of Covid-19 in the United States, according to data from Johns Hopkins University, representing about 9% of the population. But experts estimate that the actual number of cases is much higher, which accompanies the findings of the American Red Cross.
The United States Centers for Disease Control and Prevention estimates that there were more than 83 million cases by the end of December, meaning that more than a quarter of the population would be infected by the end of 2020.